Fix issues with orthographic views and points close to far plane

com.unity.perception/Runtime/GroundTruth/Resources/KeypointDepthCheck.shader

-Shader "Perception/KeypointDepthCheck"
+Shader "Perception/KeypointDepthCheckOld"
 {
     Properties
     {

com.unity.perception/Runtime/GroundTruth/Resources/KeypointDepthCheckHDRP.shader

                 float4 checkDepth = _KeypointCheckDepth.Load(float3(varyings.positionCS.xy, 0));
 
                 float depth = LoadCameraDepth(float2(checkPosition.x, _ScreenSize.y - checkPosition.y));
-                depth = LinearEyeDepth(depth, _ZBufferParams);
+                PositionInputs positionInputs = GetPositionInput(checkPosition, _ScreenSize.zw, depth, UNITY_MATRIX_I_VP, UNITY_MATRIX_V);
+                depth = positionInputs.linearDepth;
+
+                //encode and decode checkDepth to account for loss of precision with depth values close to far plane
+                float4 viewPos = mul(UNITY_MATRIX_I_VP, float4(positionInputs.positionWS.x, positionInputs.positionWS.y, checkDepth.x, 1.0));
+                float4 positionCheckWS = mul(UNITY_MATRIX_VP, viewPos);
+
+                //depth = LinearEyeDepth(depth, _ZBufferParams);
-                uint result = depth > checkDepth.x ? 1 : 0;
+                uint result = depth >= positionCheckWS.z ? 1 : 0;
                 return float4(result, result, result, 1);
             }
 #else

com.unity.perception/Tests/Runtime/GroundTruthTests/KeypointGroundTruthTests.cs

             Global,
             JointLabel
         }
+        public enum ProjectionKind
+        {
+            Orthographic,
+            Projection
+        }
 
         public static IEnumerable<(Vector3 origin, float checkDistance, float pointDistance, float cameraFieldOfView, bool expectOccluded)>
             Keypoint_InsideBox_RespectsThreshold_TestCases()
                 0.005f,
                 1f,
                 false);
+            //larger value here for the occluded check due to lack of depth precision close to far plane.
+            //We choose to mark points not occluded when the point depth and geometry depth are the same in the depth buffer
-                0.1f,
-                0.2f,
+                1f,
+                2f,
                 1f,
                 true);
         }
             [ValueSource(nameof(Keypoint_InsideBox_RespectsThreshold_TestCases))]
             (Vector3 origin, float checkDistance, float pointDistance, float cameraFieldOfView, bool expectOccluded) args,
-            [Values(CheckDistanceType.Global, CheckDistanceType.JointLabel)] CheckDistanceType checkDistanceType)
+            [Values(CheckDistanceType.Global, CheckDistanceType.JointLabel)] CheckDistanceType checkDistanceType,
+            [Values(ProjectionKind.Orthographic, ProjectionKind.Projection)] ProjectionKind projectionKind)
         {
             if (checkDistanceType == CheckDistanceType.JointLabel)
                 Assert.Inconclusive("Not yet implemented");
             var camComponent = cam.GetComponent<Camera>();
             camComponent.fieldOfView = args.cameraFieldOfView;
 
-            // camComponent.orthographic = true;
-            // camComponent.orthographicSize = .5f;
+            if (projectionKind == ProjectionKind.Orthographic)
+            {
+                camComponent.orthographic = true;
+                camComponent.orthographicSize = .5f;
+            }
 
             var cube = TestHelper.CreateLabeledCube(scale: 1f, x: args.origin.x, y: args.origin.y, z: args.origin.z);
             SetupCubeJoint(cube, template, "Center", 0f, 0f, -.5f + args.pointDistance);
             AddTestObjectForCleanup(cam);
             AddTestObjectForCleanup(cube);
 
-            // while (true)
+            //for (int i = 0; i < 10000; i++)
              yield return null;
 
             //force all async readbacks to complete